1. Field of the Invention
The present invention pertains to a new concept in fluid flow control systems such as gas flow control systems for use in semiconductor processing apparatus. Semiconductor processing utilizes inert, toxic, and corrosive gases which require the use of various flow control and filtering devices to ensure that the right quantity of contaminant-free gas reaches the semiconductor processing chamber. The control and filtering devices are assembled in clusters of elements which are typically mounted on a pallet for handling and maintenance purposes. The present disclosure makes possible the use of clusters of gas control and processing elements without the need for pipe fitting and plumbing activities which require special skill and which generate expensive down time. The general concepts involved are applicable to fluid flow systems in general.
2. Brief Description of the Background Art
There are numerous semiconductor processing steps which require the use of specialized gases. Some of these gases are inert gases such a nitrogen and argon which are generally used as diluent gases. Gases such as argon are also used for plasma creation in processes such as physical vapor deposition. In many instances the process gases are toxic or corrosive, or both. For example, in etch processing, commonly used gases include Cl.sub.2, BCl.sub.3, CCl.sub.4, SiCl.sub.4, SF.sub.6, and CF.sub.4. In chemical vapor deposition (CVD) processing, commonly used gases include H.sub.2, TiCl.sub.4, SiH.sub.4, MoCl.sub.5, WCl.sub.6, and Ta Cl.sub.5, for example. These gases require specialized handling equipment for transport, pressure reduction, filtering, mass flow control, gas mixing, and other known process-related functions.
U.S. Pat. No. 4,714,091 to Wilfried Wagner, issued Dec. 22, 1987, discloses a modular gas handling apparatus. The apparatus comprises modular flow block means, including a plurality of gas flow paths extending through the modular flow block means, to provide a plurality of port members on respective surfaces of the modular flow block means. There are a plurality of valve passages extending into the modular flow block means to provide gas flow paths at predetermined locations throughout the modular flow block means. Each of such plurality of valve passages includes an entrance aperture on a respective surface of the modular flow block means, a plurality of valve flange members, each of the valve flange members being adapted to mount a high vacuum valve on the modular flow block means at one of the entrance apertures without the need to apply rotational force the valve flange members, while providing a hermetic seal of the high vacuum valve onto the modular flow block means. In addition, each of the plurality of port members includes port member mounting means whereby conduits can be removably, hermetically sealed to the respective plurality of port members.
U.S. Pat. No. 5,188,148 to Brevard Garrison, issued Feb. 23, 1993, describes a plate structure including conduit and reagent delivery means for a fluid delivery system. The system is designed to deliver precise volumes of a plurality of fluids in sequence to a treatment reservoir. Fluid channels are formed in the plate structure to provide a means for delivering fluids from a plurality of fluid reservoirs attached to the plate structure. A partition switch is attached to the plate structure to direct fluid to the desired treatment reservoirs or pressure reservoirs.
U.S. patent application Ser. No. 08/564,466, of Manofsky Jr. et al., filed Nov. 29, 1995, and assigned to the assignee of the present application, describes flat bottom components and flat bottom architecture for fluid and gas systems. This patent application is hereby incorporated by reference in its entirety. In particular, flat bottom valves and other types of flat bottom components, such as, for example, instrumentation devices are attached to a monolithic structure having passages for interconnecting the flat bottom components.
The kinds of gas handling systems described above make it possible to use combinations of gas processing elements with minimal, if any, need to perform pipe fitting activities during installation, operation, and maintenance of the system. By pipe fitting it is meant the use of piping and tubing with various connection fittings and weldments, as generally known in the art. This has particular advantage in the semiconductor industry where, due to the corrosivity of many of the gases, frequent repair or replacement of gas handling and processing elements is required.
To be able to change out a particular element in a gas handling system when the gas which occupies the element (and conduits leading to that element) is toxic, corrosive, pyrophoric, or a combination of these, it is necessary to remove residual gas from the element and from the conduits leading to that element prior to opening the piping line and removing the element. Typically this is done by flushing out (purging) the element and associated piping with a flush gas, typically an inert gas, prior to opening the piping and removing the element. When minute concentrations of the gas may be harmful to the surrounding environment in general and/or to the person working to change out the element (hazardous), it may be necessary to use a vacuum to remove residual gas (to pump out the gas from the element), followed by purging with the flush gas, with this process repeated several times to provide for complete removal of the residual gas.
The same problems that occur with the maintenance of gas handling systems are applicable to fluids in general, including hazardous liquids. It would be highly desirable to have an apparatus which would provide for the removal of residual toxic, corrosive, or pyrophoric fluids from a fluid handling system of the kind described, where the apparatus requires minimal, if any, performance of traditional pipe fitting activities.